D8T and D9T Track-Type Tractors Caterpillar

Show/hide table

Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Probable Causes

• The setting for the margin spool in the pressure and flow compensator valve is too low.

• The circuit for signal oil has internal leakage or internal blockage.

• The pump control is suspect.

• The pump is not operating at full stroke.

• The hydraulic control valve may be worn.

• The hydraulic control valve may be worn.

Recommended Actions

Note: Care must be taken in order to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the machine. You must be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component that contains fluid. Dispose of all fluids according to local regulations.

The Setting for the Margin Spool in the Pressure and Flow Compensator Valve is Too Low

Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Piston Pump (Implement) - Test and Adjust".

Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Piston Pump (Implement) - Test and Adjust".

The Circuit for Signal Oil Has Internal Leakage or Internal Blockage

1. Make sure that the signal that is flowing to the compensator valve is not blocked.

   1. Perform the Margin Pressure Test.

      Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Piston Pump (Implement) - Test and Adjust".

      Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Piston Pump (Implement) - Test and Adjust".

   2. If necessary, adjust the flow compensator spool in order to set the correct margin pressure. If the correct margin pressure cannot be achieved, there may be blockage in the load sensing signal circuit.

      Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Piston Pump (Implement) - Test and Adjust".

      Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Piston Pump (Implement) - Test and Adjust".

   3. Repair the circuit, if necessary.

The Pump Control is Suspect

1. Make sure that the "Flow Rate" for the hydraulic control valve is adjusted correctly.

   Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Piston Pump (Implement) - Test and Adjust".

   Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Piston Pump (Implement) - Test and Adjust".

2. Check the current that is applied to the solenoid valve.

3. Make sure that the solenoid valve is functioning correctly.

   1. If necessary, repair the solenoid or replace the solenoid valve.

The Pump is Not Operating at Full Stroke

1. Make sure that the pump fully strokes. Ensure that the actuator piston moves freely and ensure that the swashplate is not blocked.

   1. Repair the pump, if necessary.

The Hydraulic Control Valve May Be Worn

1. Check for leakage around the piston seals of the hydraulic cylinders.

   Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Piston Pump (Implement) - Test and Adjust".

   Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Piston Pump (Implement) - Test and Adjust".

   1. Repair the piston seals, if necessary.

The Hydraulic Cylinder Valve May Be Worn

1. Check for a broken spring in the hydraulic control valve.

   Reference: Refer to (D8T) Specifications, Systems Operation/Testing, and Adjusting, UENR1389, "Operational Checks".

   Reference: Refer to (D9T) Specifications, Systems Operation/Testing, and Adjusting, KENR8943, "Operational Checks".

   1. Replace the spring, if necessary.